This invention relates to a control system and a method for weight filling responsive filling to bottles, flacons, and the like vessels.
As is known, weight responsive vessel filling systems generally comprise a carousel having a platform with a set of housings or loading zones and a plurality of taps, each located above every filling zone, the opening and closing command wherefor is provided by control members, such as solenoid valves, associated with members for checking the weight of the related loading zone. Every loading zone moves, during the carousel rotation, past a loading station for the empty vessels where the vessels are loaded by means of an input star which picks them up from a transport line, during the rotation of the carousel the vessels are filled to a desired weight and thereafter the filled bottles are discharged at an output station comprising a star which is effective to remove the filled bottles and eject those bottles which, following a check on completion of the filling operation, show to have weight values exceeding certain preset tolerances. Known systems further include control systems for checking the presence of the bottle prior to issue the command to open the taps.
To check the weight of the filling fluid and the presence of the bottle various systems are used which are disposed below every filling zone, e.g. by means of a load cell associated with the related filling zone which can issue electric signals correlated to the measured weight.
Such prior systems, in particular those equipped with load cells, however, require some adjustments to take into account the effects occurring due to the impact thrust generated by the free fall of a fluid, and variations related to changes in the ambient environmental conditions which occur whilst filling is being performed. In particular the thrust of the fluid falling freely from above, issuing from the tap, within the vessel generates a force interpreted as weight which, if not taken into account, would lead to false weight measurements. Furthermore, the behavior of every filling station may vary during the working cycle due to changes in the ambient environmental conditions such as changes in temperature, thus causing variations of, for example, the density and temperature of the filling fluid utilized. As a result, the device, additionally to requiring an initial calibration that takes into account the thrust of the falling fluid, also requires corrections throughout the working cycle to take into account the machine's operating conditions.
Such corrections are presently carried out mostly manually, e.g. at set time intervals or on detecting that the deviation of the filled bottles, due to weights outside of the tolerance range, exceeds an acceptable average value. However, that system, which involves the intervention of an operator, is very wasteful of material and machine operating time, both because of the need for the person to be physically present to check the machine's operation, and because prior to effecting the correction the number of discarded vessels is increased owing to their being out of tolerance, or the error existing in every vessel with respect to the nominal value even if within the tolerance range.